North Rail Connector Project

Environmental Assessment

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Appendix C – Escatawpa River Phase One Total Maximum Daily Load for Mercury
Escatawpa River 

Phase One 

Total Maximum Daily

Load 

for 

Mercury 

J UNE 26, 2000 

APPROVED VERSION 

Pascagoula Basin

Jackson and 

George Counties,

Mississippi 

Prepared By

Mississippi Department of Environmental Quality 

Office of Pollution Control

TMDL/WLA Section/ 

Water Quality Assessment Branch 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

FOREWORD 

This report has been prepared in accordance with the schedule contained within the federal 

consent decree dated December 22, 1998. (Sierra Club v. Hankinson, No. 97-CV-3683 (N.D. 

Ga.)) The report contains one or more Total Maximum Daily Loads (TMDLs) for waterbody 

segments found on Mississippi's 1996 Section 303(d) List oflmpaired Waterbodies. Because of 

the accelerated schedule required by the consent decree, many of these TMDLs have been 

prepared out of sequence with the State's rotating basin approach. The segments addressed are 

comprised of monitored segments that have data indicating impairment. The implementation of 

the TMDLs contained herein will be prioritized within Mississippi's rotating basin approach. 

The amount and quality of the data on which this report is based are limited. As additional 

information becomes available, the TMDLs may be updated. Such additional information may 

include water quality and quantity data, changes in pollutant loadings, modification to state water 

quality criteria, or changes in landuse within the watershed. In some cases, additional water 

quality data may indicate that no impairment exists. 

Prefixes for fractions and multiples of SI units 

Fraction Prefix S mbol Multi le Prefix S mbol 

1 o· deci d 

10-2 centi C 

10-3 milli m 

10-6 micro μ 

10-9 nano n 

10-12 pico p 10-15 femto f 

10-18 atto a 

10 deka da 

10 2 hecto h 

10 3 kilo k 6 10 mega M 

10 9 giga G 

10 12 tera T 

10 15 peta p 

10 18 exa E 

Conversion Factors 

To convert from To Multi I b To Convert from To Multi I 

Acres Sq. miles 0.0015625 Days Seconds 86400 

Cubic feet Cu. Meter 0.028316847 Feet Meters 0.3048 

Cubic feet Gallons 7.4805195 Gallons Cu feet 0.133680555 

Cubic feet Liters 28.316847 Hectares Acres 2.4710538 

cfs Gal/min 448.83117 Miles Meters 1609.344 

cfs MGD .6463168 Mg/I ppm 1 

Cubic meters Gallons 264.17205 /I* cfs Gm/day 2.45 

11 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

CONTENTS 

Page 

SEGMENT IDENTIFICATION .. ................................................................................................... v 

EXECUTIVE SUMMARY .......................................................................................................... viii 

1.0 INTRODUCTION ................................................................................................ ..................... 1 

1.1 BACKGROUND ................................................................................................................... 1 

1.2 PHASED TMDL APPROACH ............................................................................................ 1 

1.3 W ATERBODY SEGMENT LOCATION ............................................................................ 1 

1.4 WATERBODY DESIGNATED USE .................................................................................. 3 

1.5 APPLICABLE WATER QUALITY STANDARDS ............................................................ 3 

2.0 TMDL ENDPOINT AND WATER QUALITY ASSESSMENT .. ......... ............ ............ ......... 8 

2.1 SELECTION OF A TMDL ENDPOINT AND CRITICAL CONDITION ................ ......... 8 

2.1.1 Mercury Speciation and Chemistry ................................................................................ 8 

2.1.2 Mercury Transport and Transformations .............. ........................ ................................. 9 

2.1.3 Mississippi Mercury Criteria (Fresh Water) ........................ ............ ............................ 10 

2.1.4 Mississippi Regulations on Flow determination .......................................................... 11 

2.2 DISCUSSION OF INSTREAM WATER QUALITY ........................................................ 11 

2. 2 .1 Inventory of Water Quality Monitoring Data .............................................................. 11 

2.2.2 Analysis of Fish Tissue Data ........................................................................................ 12 

3.0 SOURCE ASSESSMENT ........... ............ ............ ............ ....................................................... 13 

4.0 MODELING PROCEDURE ................................................................................................... 14 

4. 1 MODELING CALCULATIONS ......... ................................................ ............................... 14 

4.2 CALCULATION SETUP ................................................................................ ................... 14 

4.3 STREAM CHARACTERISTICS ....................................................................................... 14 

4.4 SOURCE REPRESENTATION ......................................................................................... 15 

5.0 ALLOCATION ....................................................................................................................... 16 

5.1 TMDLCALCULATION .................................................................................................... 16 

5.2 TMDL ALLOCATIONS .................................................................................................... 16 

5.3 INCORPORATION OF A MARGIN OF SAFETY ................ ........................ ................... 17 

5.4 SEASONALITY ................................................................................................................. 18 

5.5 IMPLEMENTATION PLAN .............................................................................................. 19 

6.0 CONCLUSION ........................................ ........................ ........................ ........................ ....... 20 

6.1 FOLLOW-UP MONITORING ........................................................................................... 20 

6.2 PUBLIC PARTICIPATION ............................................................................................... 20 

DEFINITIONS ...................................... ................................................................................. ....... 21 

ABBREVIATIONS ....................................................................................................................... 25 

REFERENCES .............................................................................................................................. 26 

111 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

APPENDIX A Fish Flesh Mercury Data in the Escatawpa River ................................................ 27 

APPENDIX B Fish Advisory for Mercury in the Escatawpa River ............................................. 28 

TABLE 1 Waterbody Identification for the Escatawpa River TMDL. .......................................... 2 

TABLE 2 Subwatersheds in HUC 03170008 ............................................................................... 2 

TABLE 3 Land use Distribution in Escatawpa River Watershed (acres) ...................................... 3 

TABLE 4 State of Mississippi Water Quality Criteria for Intrastate, Interstate, and Coastal 

Waters .......................................................................................................................... 4 

TABLE 5 Fish Tissue Station Data Inventory .............................................................................. 9 

TABLE 6 Water Quality Station Data Analysis ......................................................................... 10 

TABLE 7 Permitted Facilities in Escatawpa River Watershed ................................................. 11 

TABLE 8 Mercury Permitted Facilities in Escatawpa River Watershed .................................... 13 

TABLE 9 TMDL for Total Mercury 11 ....................................................................................... 14 

TABLE 10 Facilities Requiring Mercury Effluent Testing .......................................................... 15 

FIGURE 1 Area Location Map ....................................................................................................... 2 

FIGURE 2 Watershed Map ............................................................................................................. 5 

FIGURE 3 Watershed Segment Map .............................................................................................. 6 

FIGURE 4 Landuse Map ................................................................................................................ 7 

FIGURE 5 TMDL Allocation Pie Chart ....................................................................................... 18 

lV 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

NON-IMPAIRED SEGMENT IDENTIFICATION 

Name: Escatawpa River, Segment 3 (Salt Water) 

Waterbody ID: MS107M3 

Location: Near Moss Point: from Interstate 10 Bridge to mouth at the 

Pascagoula River 

Counties: Jackson 

USGS HUC Code: 03170008 

NRCS Watershed: 080 

Length: 10 miles 

Use Impairment: A fish consumption advisory is not posted for this waterbody. 

Current fish flesh data show mercury levels below the FDA action 

level. 

Cause Noted: NIA 

Standards Variance: NIA 

Pollutant Standard: Mercury II, total chronic fresh water concentration may not exceed 

0.012 μg/1 expressed as total recoverable, 

Mercury II, total chronic salt water concentration may not exceed 

0.025 μg/1 expressed as total recoverable 

This segment is not classified as fresh water. The salt content is 

routinely 20 parts per thousand. 

Vll 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

EXECUTIVE SUMMARY 

The fresh water portions of the Escatawpa River, identified as Segments 1 and 2 in this report, 

are impaired by mercury. Largemouth bass and catfish caught in these segments have been 

sampled and the data show a definite impairment due to levels of mercury in the fish flesh, which 

exceed the FDA Action level. 

Based on this data, the State of Mississippi issued a fish consumption advisory (See Appendix B) 

for Segment 1 and 2 of the Escatawpa River. This advisory was issued to help protect the people 

who regularly consume fish caught in this river. The bioaccumulation of methylmercury in fish 

flesh is the basis for the impairment in this stream. 

This Phase One Mercury TMDL for the Escatawpa River has been developed prior to a complete 

understanding of the linkage between mercury in the water and mercury in the fish. There are no 

NPDES permitted dischargers currently in Segments 1 or 2. All of the dischargers are in 

Segment 3. However, Segment 3 does not have an advisory for mercury; there have been no fish 

sampled from Segment 3 with elevated mercury levels; and MDEQ intends to delist Segment 3 

from the next Section 303( d) list. This segment is downstream of Segment 2, which is impaired 

for mercury. There is some process within the mercury cycle that is causing this phenomenon. 

Additionally, this Phase One Mercury TMDL is only concerned with point source contributions 

to the waterbody. Atmospheric deposition, nonpoint source contributions, and natural 

background will be considered in Phase Two. It is anticipated that the mercury data generated 

from the point source contributors during the next few years will enhance the knowledge base on 

this issue. 

The endpoints selected for this Phase One Mercury TMDL are based on MDEQ regulations. 

There are several mercury criteria to evaluate. The human health criterion is currently 153 ng/1 

of total mercury. The aquatic life support criteria are 12 ng/1 fresh water and 25 ng/1 salt water of 

total mercury II expressed as total recoverable. Recent EPA criteria guidance has suggested that 

each of these numbers be revised. The 153 ng/1 criterion has been proposed to be reduced by 

2/3. The aquatic life support numbers have been proposed to increase to a more representative 

value of 770 ng/1 and 940 ng/1, respectively. However, these new numbers have not been 

adopted by the Mississippi Commission on Environmental Quality. MDEQ is therefore going to 

use the most protective of the currently available criteria. 

By using the 12 ng/1 criterion as the target, a large implicit margin of safety is created. However, 

to further account for the unknowns, an additional explicit margin of safety is included in this 

TMDL. This explicit margin of safety is set at 75%. 

The implementation plan in this Phase One TMDL calls for a moratorium on any mercury 

discharge in Segments 1 and 2. It also calls for increased monitoring for dischargers in Segment 

3. Although Segment 3 is downstream of the impaired segment, and, as mentioned above, no 

elevated levels of mercury have been found in fish, dischargers to Segment 3 should monitor 

their effiuents for mercury. 

Vlll 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

1.0 INTRODUCTION 

1.1 BACKGROUND 

The identification of waterbodies not meeting their designated use and the development of total 

maximum daily loads (TMDLs) for those waterbodies are required by Section 303(d) of the 

Clean Water Act. This is also a requirement of the Environmental Protection Agency's (EPA) 

Water Quality Planning and Management Regulations ( 40 CFR Part 130). The TMDL process is 

designed to restore and maintain the quality of those impaired waterbodies through the 

establishment of pollutant specific allowable loads. The pollutant of concern for this TMDL is 

mercury. The purpose of this TMDL is to establish water quality objectives and best 

management practices to reduce the mercury levels currently found in fish flesh taken from the 

Escatawpa River. 

Human exposure to inorganic mercury in large amounts can cause a variety of health effects. 

The two organ systems most likely affected are the central nervous system and the kidney. 

However, the most significant concerns regarding chronic exposure to low concentrations of 

methylmercury in fish are for neurological effects on the developing fetus and children.1 

1.2 PHASED TMDL APPROACH 

This document is Phase One of a multi-phase TMDL being developed for mercury in the 

Escatawpa River. This Phase One Mercury TMDL will determine the maximum load of 

mercury that should be introduced into the impaired segments based on Mississippi's current 

water quality criteria. Phase Two of this TMDL project, to be completed at a later date, will 

quantify the mercury load to the Escatawpa River that is directly related to atmospheric sources 

and other nonpoint sources. Phase Two will also attempt to include a fate and transport model 

for the river that will better characterize aquatic mercury cycling. 

1.3 WATERBODY SEGMENT LOCATION 

As summarized in Table 1, Segment 1 of the Escatawpa River begins at the Alabama -

Mississippi State line and ends at the confluence with Spring Creek east of Hurley. Segment 2 

starts at the confluence with Spring Creek and ends at the Interstate 10 Bridge. Segment 3 

begins at the I-10 Bridge and continues to the mouth of the river into the Pascagoula River. The 

upstream segment located in Alabama is not included in this TMDL project. 

The entire drainage area of the Escatawpa River (USGS Hydrologic Unit Code (HUC) 

03170008) is approximately 1,031 square miles. The Escatawpa River Watershed has been 

divided into four subwatersheds for this TMDL study, representing the two impaired segments, 

the downstream segment, and the upstream segment located in Alabama. The watershed 

contains urban areas including Pascagoula and Moss Point, and a number of small suburban 

communities. A majority of the landuse is forest. 

1 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

In an attempt to protect human health, Mississippi has issued a Fish Consumption Advisory for 

Segments 1 and 2 of the Escatawpa River. This advisory was issued due to elevated levels of 

mercury found in fish flesh collected in these segments. See Appendix B. There is no advisory

for Segment 3. Data indicate there is no mercury impairment in Segment 3. 

Figure 1 Area Map 

T abl e 1 W ater b o d Id ent1 ifi1cat1on f or t h e E scatawpa R 1ver TMDL 

Waterbody 

Name 

Stale 

Waterbodv ID 

Assessment 

type

Size Co11nty Listed 

Advisory

Advisory

Cause 

Escatawpa 

River, Seg 1 

MS107M1 Monitored 20 mi George, 

Jackson 

Fish 

Consumption 

Advisory 

Mercury 

Location - Near Agricola: from Alabama state line to confluence with Spring Creek e as! of Hurley 

Escatawpa 

River, Seg 2 

MS107M2 Monitored 24 mi Jackson Fish 

Consumption 

Advisory 

Mercury 

Location - Near Orange Grove: from co nflue nee with Spring Creek east of Hurley to 1-10 

Escatawpa 

River, Seg 3 

MS107M3 Monitored 10 mi Jackson No 

Advisories 

None 

Location - Near Escatawpa: from 1-10 Bridge to mouth at Pascagoula River 

2 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

Table 2 Subwatersheds in HUC 03170008 

Waterbody Segment Name Waterbody Seg. ID Subwtshd. ID Number 

Escatawpa River, Alabama Segment n/a 031700080a 

Escatawpa River, Segment 1 MS107M1 0317000801 

Escatawpa River, Segment 2 MS107M2 0317000802 

Escatawpa River, Segment 3 MS107M3 0317000803 

Table 3 Land use Distribution in Escatawpa River Watershed (acres) 

Watershed Urban Agricultural Forest Water Wetland Barren Total 

031700080a 657 33,757 304,719 204 409 1,356 341,102 

0317000801 58 19,444 38,297 45 2,812 10 60,666 

0317000802 4,981 74,077 121,792 3,615 5,790 482 210,737 

0317000803 4,138 6,432 28,818 780 7,186 160 47,514 

Total 9,834 133,710 493,626 4,644 16,197 2,008 660,019 

Percent 1% 20% 75% 1% 2% 0% 100% 

1.4 WATERBODY DESIGNATED USE 

Designated beneficial uses and water quality standards are established by the State of Mississippi 

in the Water Quality Criteria for Intrastate, Interstate and Coastal Waters regulations. These 

regulations set the criteria concentrations for pollutants and methods for calculating loads based 

on the standards. MDEQ regulations require the use of these standards for establishing loads for 

Mississippi waters. The standards for this river have been established based on a designated use 

of Fish and Wildlife. 

1.5 APPLICABLE WATER QUALITY STANDARDS 

Mercury is included within MDEQ regulations as a toxic substance. The standards specifically 

set the numeric criteria and calculation methods for dete1mining the loading from sources for this 

pollutant. 

Indications are apparent that the standard may soon be changing for each of the mercury species 

included in the criteria. However, until the stakeholders within Mississippi are allowed to 

partake in the process to change Mississippi criteria and the Mississippi Commission on 

Environmental Quality adopts any modification, using another concentration value for mercury 

or calculation method would be an arbitrary and capricious decision. The water quality 

standards applicable to the uses of the waterbody segments and the pollutant of concern are listed 

in Table 4 as defined by the State of Mississippi Water Quality Criteria for Intrastate, Interstate, 

and Coastal Waters regulations. 

3 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

Table 4 State of Mississippi Water Quality Criteria for Intrastate, Interstate, and Coastal Waters 

Parameter Beneficial 

use 

Water Quality Criteria 

Total Mercury Public Water 

Supply 

Concentration may not exceed 0.151 μg/1 

Total Mercury Fish 

Consumption 

Concentration may not exceed 0.153 μg/I 

Mercury (11) Aquatic Life Fresh Water 

total dissolved Support Acute: instantaneous concentration may not exceed 2.1 μg/I 

Hg(II) Chronic: average concentration may not exceed 0.012 μg/I 

expressed as total expressed as total recoverable 

recoverable 

Salt Water 

Acute: instantaneous concentration may not exceed 1.8 μg/I 

Chronic: average concentration may not exceed 0.025 μg/I 

expressed as total recoverable 

4 
Phase One Mercury TMDL for Escatawpa River, Mississippi

Figure 2 

ESCATAWPA RIVER 

WATERSHED 

Pascagoula 

River 

s 

0 15 30 miles 

/\/ Reach File. V1 

Cataloging Unit Boundaries 

Major Roads 

Urban Area Boundaries 

County Boundaries 

State Boundaries 

5 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

Fi ure 3 

ESCATAWPA RIVER 

SUBWATERSHEDS 

s 

0 10 miles 

D Subwatershed Boundaries 

/\/ Reach File, V1 

D Cataloging Unit Boundaries 

/\/ Major Roads 

D County Boundaries 

D State Boundaries 

6 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

Fi ure4 

ESCATAWPA WATERSHED 

LANDUSE 

Land Use Type 

Urban or Built-up Land 

- Agricultural Land 

D Rangeland 

- Forest Land 

- Water 

D Barren Land 

6 

--

0 

- 6 

- 12 Miles 

s 

7 
Phase One Mercury TMDL for Escatawpa River, Mississippi 

6.0 CONCLUSION 

MDEQ will not approve any NPDES Permit application for Segments 1 and 2 that does not 

comply with the moratorium for mercury discharges into Segments 1 and 2. In addition, this 

TMDL requires all NPDES Permitted dischargers in Segment 3 to monitor for mercury using 

clean techniques and accurate testing methods. 

Phase Two of this TMDL will include nonpoint sources of mercury, atmospheric deposition, and 

will consider the effects of mercury cycling in the river. The TMDL calculations from Phase 

One may be revised in Phase Two of this TMDL since more will be known about the percentage 

of mercury contributions from point and nonpoint sources. 

6.1 FOLLOW-UP MONITORING 

Additional ambient mercury monitoring for all species of mercury will be needed for 

development of Phase Two. Additional information is required to facilitate the understanding of 

the methylmercury process and the linkage between mercury in the water column and mercury in 

fish flesh. Specialized monitoring approaches will also be needed to determine the atmospheric 

deposition contribution to mercury in the watershed. 

MDEQ has adopted the Basin Approach to Water Quality Management, a plan that divides 

Mississippi's major drainage basins into five groups. During each yearlong cycle, MDEQ 

resources for water quality monitoring are focused on one of the basin groups. During the next 

monitoring phase in the Pascagoula Basin, the Escatawpa River will receive additional 

monitoring to identify the improvements in water quality gained from the implementation of the 

Phase One strategy included in this TMDL. 

6.2 PUBLIC PARTICIPATION 

This Phase One TMDL project will be published for a 30-day public notice. During this time, 

the public will be notified by publication in the statewide newspaper and a newspaper in 

Pascagoula. The public will be given an opportunity to review the TMDL and submit comments. 

All comments received during the public notice period and at any public hearings become a part 

of the record of this TMDL. All comments will be considered in the ultimate approval of this 

TMDL and for submission of this TMDL to EPA Region 4 for final approval. 

20